This invention relates to packaging liquids, and relates particularly to packaging liquids such as unfortified wines, which deteriorate when exposed to air, in packages formed from heat-sealable substantially air-impermeable plastics material.
It has been proposed to provide a rigid container having disposed therein a flexible bag or lining of a film formed from a material such as ethyl vinylacetate coated with polyvinylidene chloride for holding liquid stored in this container. Means are provided at or near the base of the container for tapping the container so that liquid therein may be withdrawn therefrom. Such means include a dispensing closure or tap located in a wall of the bag or the lining, whereby the liquid therein may be dispensed in desired quantities.
The container may also be provided with a vent, usually at or near its upper end, so that when liquid is withdrawn from within the flexible lining air will flow into the container outside the flexible lining to cause the lining to collapse around the liquid remaining in it. In this form of container the air admitted through the vent does not come in contact with the liquid, so that even a liquid which deteriorates when exposed to air may be stored for an appreciable period. Such containers are hereinafter referred to as "bag-in-box" containers.
Generally bag-in-box containers are supplied to packagers in the form of separate components which may be readily assembled. For example, the components may be a cardboard box blank, a single or multilayered flexible bag having an open socket through which the bag may be filled with liquid, and a tap adapted to fit onto the socket. Alternatively, the bags may be open-ended with a closed socket such that they may be filled through the open ends and subsequently heat sealed.
During the time which elapses between manufacture of the flexible bags and filling of the bags with liquid, there is always the risk that the interior of the bags will become contaminated with bacteria or mould which may enter the bags through the open sockets or ends. Thus, packagers, in order to minimize contamination, are obliged to use the bags as soon as possible rather than keep them in storage for long periods as sterilization of the bags prior to filling is difficult.
In addition, when filling through the socket the narrowness of the socket opening makes very rapid filling of the bags with liquid difficult. Furthermore, considerable manual labor and time is required for the filling of the individual bags irrespective of whether they are filled through an open socket or an open end.
Yet another disadvantage of using pre-formed bags is that a shipment of bags may be manufactured and sent to a packager who finds that the seals on a number of the bags are not leak-proof. This may be caused by the use of incorrect heat sealing settings on the bag manufacturing machines of the bag manufacturer. As the manufacturer has no practical way of testing all his bags, a complete shipment or production run of bags may have to be scrapped because of a few defective bags.
It is also known to produce, and fill with liquid or another flowable substance, packages formed from heat-sealable, air-impermeable sheet material.
The production and filling of such packages is normally carried out by form/fill/seal machines. In general, form/fill/seal machines operate by folding a web of heat sealable film such as a single thickness cellulose acetate web coated on both sides with polyethylene or polyvinylidene chloride combined with ethylvinyl acetate upon itself along its length, heat sealing the overlapped portion of the lengthwise fold to form a tube and closing the bottom of the tube formed in this manner by a heat seal. Prior to, or during the heat sealing and folding operations the web is usually sterilized by irradiation with ultra-violet light to reduce the risk of contamination by mould or fungi. A measured amount of liquid is introduced into the open end of the tube and a portion of the tube is again heat sealed to form a sealed bag containing liquid. Thus the second heat seal forms the bottom seal for a succeeding bag and the filling operation is repeated. The heat seal between the succeeding bags is then separated to form separate liquid filled bags. As the filling operation is automatic and requires no manual labor, the rate of filling can be increased substantially over that of the prior described methods.
Furthermore, any incorrect setting of the seal forming mechanism of the form/fill/seal machine can be immediately detected because of leakage from the bags being formed. Hence it is possible to make immediate adjustment to the sealing machine settings with a consequent minimisation of lost production and wasted bag marking materials.
Packages produced by form/fill/seal machines are unsuitable for use in bag-in-box containers, as the packages do not contain means whereby the liquid in the package may be dispensed.